1. Field of the Invention
The present invention relates generally to connection-oriented networks and more specifically to a network node having a first-in-first-out buffer for multiple connections.
2. Description of the Related Art
Japanese Laid-Open Patent Specification Hei-8-274793 describes a connection-oriented communication system which ensures minimum bandwidth for established virtual connections using a plurality of buffers associated respectively with the established connections. Japanese Laid-Open Patent Specification Hei-9-83547 discloses a connection-oriented communication system in which a plurality of buffers are provided to ensure minimum bandwidth for each buffer. However, the use of individual buffers for multiple connections would require a significant number of buffers if a large number of connections must be supported This also results in a significant increase both in complexity and hardware for implementing circuitry for controlling the buffers. In contrast, a single-buffer approach is disclosed in Japanese Laid-Open Patent Specification Hei-7-95209 in which a single buffer is commonly shared by all virtual connections for admission control procedure. In this procedure, the transmission rate of each connection is compared with the contract value of the connection. If the transmission rate of a connection exceeds its contract value, the packets of this connection are discarded. However, if this approach were used in a network node, the output transmission medium of the node cannot be utilized to its maximum efficiency.